Eye anatomy (1)

Eye

is the organ of sight and consists the eyeball and accessory structures.

Extraocular Muscles

Muscles that control the movement of the eyeball.

Orbit

Components of the bony orbit include the frontal lacrimal, zygomatic, presphenoid, basisphenoid, and palatine bones.

Periorbital fascia

The connective tissue surrounding the eye for cushioning.

Eye adnexa

The attachment or appendages involved in protecting and supporting the function of the eye.

Eyelids (Palpebrae)

Thin layers of skin that cover the eye.

Nictitating membrane

palpebral tertia; a third eyelid present in dogs.

Tarsus

A fibrous plate supporting the margin of the eyelid

Meibomian gland

A gland located in the tarsus that produces oily secretions.

Conjunctiva

A special mucous membrane lining the eyelid and the eyeball.

Palpebral Conjunctiva

lines the inner surface of the eyelid

Bulbar Conjunctiva

reflection of the palpebral conjunctiva into the eyeball

Lacrimal apparatus

The system involved in tear production and drainage.

Lacrimal Gland

secretes the tears

Lacrimal Duct and Sac

conveys the tears into the nasal cavity

Lacrimal Caruncle

is the triangular prominence in the medial canthus

Lacrimal Puncta

are the openings into the lacrimal canal on the upper and lower eyelid near medial canthus

Canthus

The point where the eyelids meet.

Medial Canthus

point where the eyelids meet at the medial side

Lateral Canthus

point where the eyelids meet at the lateral side

Eye Tunics

layers of the eye; 3 layers, fibrous, vascular, and nervous

Fibrous tunic

The outer layer of the eyeball consisting of the sclera and cornea.

Sclera

The white part of the eye.

Cornea

The transparent anterior part of the eye.

Limbus

junction between the sclera and cornea

Vascular Tunic (uvea)

Middle layer of the eye made up of the choroid, ciliary body, and iris

Iris

The colored part of the eye surrounding the pupil.

Pupillary Constrictor

circular muscle constricting the pupil

Pupillary Dilator

radiating smooth muscle dilating the pupil

Pupil

central opening of the iris that lets light into the eye

Choroid

The posterior part of the vascular tunic that supplies the retina and absorbs light.

Ciliary body

The thickest portion of the vascular tunic that alters the shape of the lens.

Nervous Tunic

inner layer made up of the retina

Retina

The inner coat of the eye responsible for image formation.

Photoreceptors

The light-sensitive cells in the retina, including rods and cones.

Rods

sensitive to dim light and shape, motion

Cones

sensitive to color and sharpness of vision

Blind Spot

no image detection in this are due to presence of optic disc

Optic Disc

area on retina where the axons of the ganglion neuron leave the eye as the optic nerve; it’s a blind spot due to no rods or cones

Bipolar Neuron

intermediate layer, receives impulse from rods and cones and passes to neuronal ganglia

Ganglion Neuron

inner layer passing impulse to optic nerve

Lens

The transparent, biconvex body of the eye that focuses light onto the retina.

Eye Chambers

filled with fluids; anterior and posterior chambers are filled with clear watery fluid

Aqueous humor

The clear watery fluid filling the anterior and posterior chambers of the eye.

Vitreous humor

The thick gel-like fluid filling the space behind the lens.

Anterior Chamber

between the iris and cornea

Posterior Chamber

between iris, ciliary body and lens

Vitreous Chamber

behind lens surrounded by retina

4 Straight Muscles

Lateral Straight M - contracts when eye moves to the lateral side

Medial Straight M

Dorsal Straight M

Ventral Staight M

2 Oblique - Rotation Muscles

Ventral Oblique

Dorsal Oblique

Retractor Muscle

surrounds the optic nerve